Delivery with Chitosan-coated Liposomes and Other Topics: Literature Findings

By: Charles Fox, Independent Consultant

Posted: February 26, 2009, from the March 2009 issue of Cosmetics & Toiletries.

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Water-soluble UV filter: Beiersdorf AG discloses cosmetic preparations with water-soluble UV filters and a vinylpyrrolidone/acrylic acid copolymer.¹² The cosmetic preparations contain one or more water-soluble UV photoprotective filters selected from 2-phenylbenzimidazole-5-sulfonic acid and the sodium, potassium and triethanol ammonium salts thereof, as well as phenylene-1,4-bis-(2-benzimidazyl)-3,3’-5,5’-tetrasulfonic acid and the sodium, potassium and triethanolammonium salts thereof; and a copolymer of vinylpyrrolidone and acrylic acid. An example is shown in Formula 7.

Interesting Compositions
Lipid microemulsions: Cargill Inc. has been issued a patent on lipid microemulsions.¹⁴ The described microemulsions include an aqueous component, a lipid (e.g., sterol esters or omega-3 fatty acids), a saccharide, an alcohol, and an emulsifier. The microemulsion is produced by first adding the saccharide to the aqueous liquid to form a mixture, then adding an alcohol and emulsifier to the mixture and finally adding a lipid to the mixture to form a microemulsion. An example is shown in Formula 8. Food or beverage products including a microemulsion are also disclosed in the patent.

Catechin and surfactant antibacterial detergents: Kao Corp. introduced antibacterial detergent compositions containing catechins and surfactants, and a method for imparting antibacterial activity on various compositions.¹⁵ The compositions contain 0.0005–5% catechins and 0.00001–80% cationic, amphoteric and/or nonionic surfactants. The method involves adding the above compositions to cosmetics, quasi drugs, pharmaceuticals, and household products. Thus, a combined use of catechin^c and a surfactant chosen from lauramine oxide, alkylbenzyl dimethyl ammonium chloride^d and glyceryl laurate^e showed synergistic antibacterial activity^c.

Methodology
Rheology in stable, tactile cosmetics: Akatsuka has reviewed the application of rheology properties for developing highly stable and tactile cosmetics.¹⁶ The rheological properties of ternary systems containing single-chain cationic surfactants, long-chain alcohols and water were studied to enhance their long-term stability and usability. The basic ternary systems behave as solids at low stress, due to the formation of alpha-gels. Adding a double-chain cationic surfactant to a ternary system causes the rupture of the alpha-gels, transforming them to vesicles. Thus, the viscosity of the system as well as its stability was lowered significantly.

The effect of polyols on the rheological properties of ternary systems also was studied to improve their usability against shear forces. External shear to ternary systems causes the rupture of gel structures and the systems are converted from solid-like bodies to viscoelastic liquids. The mechanism resulting in the rheological changes is the release of bound water in lamella liquid crystals without rupture of lipophilic layers.